A vehicle generally comprises a power source such as an electric motor or an internal combustion engine (ICE) with a power output in the form of a rotating crank shaft. For automatic transmission vehicles, the rotating crank shaft is coupled to a torque converter and to a transmission in order to convert the rotating power output to torque for drive wheels. Conventionally, the crank shaft from the ICE is connected to the torque converter via a flexplate. Furthermore, the torque converter in an automatic transmission vehicle generally includes a lock-up clutch to eliminate slip in the torque converter. Moreover, a damper system is required for absorbing irregularities in the power output from the ICE which otherwise may be harmful for the transmission of the vehicle or create noise and vibrations. In case of a hybrid vehicle, additional components for a power take off for an electric motor may be located between the ICE and the transmission or directly connected to the transmission.
In addition to the above described components of a conventional vehicle powertrain, further components are needed to meet a present demand to increase the number of gears, improve the damping systems, increase torque output to the drive wheels, etc. Accordingly, as the vehicles become more sophisticated, the number of components in the powertrain of the vehicle appears to increase. This development is in contrast with the size of new vehicle models tending to be substantially the same compared to previous similar vehicle models, or even following a down-sizing trend.
One exemplary situation in which space is limited is for the installation of a flexplate. A flexplate is typically mounted between the crank shaft and the torque converter with screw joints. However, the installation length of the screw joints is relatively large in the cramped space between the torque converter and the ICE. In powertrain assembly the screw joints for the flexplate may thus lead to tedious and possibly time consuming work.
An example of a torque converter coupled to a crank shaft of a vehicle is described in KR20070114860. Here, the crank shaft from the ICE is directly connected to the torque converter via a spline connection. Torque fluctuations from the ICE will be directly transmitted to the spline connection which may not be a sustainable solution due to for example the durability of the spline connection and may in some cases (e.g. for a diesel ICE) create noise issues.
There is thus a need for a more compact solution for allowing controllable torque transmission between the ICE and the transmission of a vehicle.